Diabetes is a metabolic disorder which is characterized by hyperglycemia, disturbance in antioxidants enzymatic function, glycosylated hemoglobin and high oxidative stress which may lead to many severe health complications. Among these complications, cardiovascular disease is of great concern. Deficiency of Vitamin C is very common in diabetic patients and low vitamin C level is supposed to be gateway for metabolic disorder progression like diabetes and cardiovascular diseases.
WHY PLASMA CONCENTRATION OF VITAMIN C IS LOW IN DIABETIC PATIENTS?
Vitamin C plasma concentration is usually sub normal or low in diabetic patients may be due to oxidative stress and inflammation because of visceral or abdominal fat (obesity), excessive excretion of vitamin C through urine and due to competition between blood glucose and vitamin C for absorption into cell.
VITAMIN C AS A POTENT ANTIOXIDANT
Vitamin C is a potent, fundamental and powerful antioxidant which reduces oxidative stress by scavenging free radicals which is responsible for damage to cell. It releases nitric oxide into blood vessels and promote vasodilation and subsequently reduces blood pressure. Vitamin C prevents atherosclerosis (hardening) of blood vessels by preventing oxidative changes in LDL (bad cholesterol) responsible for plaque formation.
EFFECTIVENESS OF VITAMIN C IN REDUCING CARDIOVASCULAR RISK IN DIABETIC PATIENTS
Due to antioxidant effects of vitamin C, it is hypothesized to be protective against cardiovascular diseases and helpful in managing diabetes in patients (Oxidative stress is the common factor for cardiovascular diseases and diabetes progression). The study’s results about vitamin C effectiveness in reducing cardiovascular risk in diabetic patients is mixed. However non conclusive and non-definitive evidences of recent study indicates that high vitamin C supplements intake increases the risk of cardiovascular diseases in postmenopausal diabetic women. Why it happens? Let’s check out.
POSSIBLE MECHANISM OF ACTION OF VITAMIN C IN INCREASING THE RISK OF CVS DISEASE IN DIABETIC WOMEN?
The following possible mechanism of actions are involved in increasing the risk of CVS disease in diabetic women
PRO-OXIDATIVE EFFECTS OF VITAMIN C
In the diabetic patients in the presence of excess iron due to disturbance in iron metabolism vitamin C supplements act as pro-oxidant which increases oxidative stress. As a result of it, there is free radical availability which damage the cells and raise the risk of CVS disease.
EFFECTS ON BLOOD VESSELS
High doses of vitamin C disrupt endothelial function of blood vessels. As a result of which, there is less availability of nitric oxide which is helpful in vasodilation of blood vessels and in maintaining normal blood pressure.
FORMATION OF GLYCATED PROTEIN
Vitamin C in high doses form a glycated protein with glucose which promote atherosclerosis which is one of the main leading causes of heart attack.
IS DIETARY VITAMIN C ALSO INCREASES RISK OF CVS DISEASES LIKE VITAMIN C SUPPLEMENTS?
Dietary vitamin C may have protective effects against cardiovascular diseases.
WHY THIS DIFFERENCE EXITS?
It is not clear whether taking vitamin C from dietary sources or from supplement is beneficial against cardiovascular diseases but it is believed that dietary vitamin C is good for cardiovascular health than supplemental vitamin C may be due to presence of other vitamins. The reason behind differential activity of naturally occurring and supplemental vitamin C is primarily because of balance present between oxidize and reduce redox agent in dietary sources along with fiber, minerals, other vitamins and phytochemicals while supplemental vitamin C lack this balance. May be due to this, dietary vitamin C act differently (beneficial in cardiovascular diseases) as compare to supplemental vitamin C (in high doses show pro- oxidative effects).
CONCLUSION
We can say that high doses of vitamin C supplements is the risk factor of cardiovascular diseases in postmenopausal diabetic women while dietary vitamin C may have protective effects in reducing risk of cardiovascular diseases in diabetic patients. Future research may help us in making conclusive and definitive opinion about the cardiovascular risk associated with high doses of supplemental vitamin C in diabetic patients.
